[知了堂学习笔记]代码生成唯一id（并发量不大的情况下）

package com.finalcial.util;

import java.text.DecimalFormat;
import java.text.FieldPosition;
import java.text.Format;
import java.text.NumberFormat;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.logging.Logger;

/**
* 生成唯一的时间id
* @author Administrator
*
*/
public class TimeIdUtil {

public TimeIdUtil() {
}

private static final Logger logger = Logger.getLogger("log");
private static final FieldPosition HELPER_POSITION = new FieldPosition(0);
private final static Format dateFormat = new SimpleDateFormat("YYYYMMddHHmmssS");
private final static NumberFormat numberFormat = new DecimalFormat("0000");
private static int seq = 0;
private static final int MAX = 9999;

/**
* 时间格式生成序列
* @return
*/
public static synchronized String getId() {
Calendar rightNow = Calendar.getInstance();
StringBuffer sb = new StringBuffer();
dateFormat.format(rightNow.getTime(), sb,HELPER_POSITION);
numberFormat.format(seq, sb, HELPER_POSITION);
if (seq == MAX) {
seq = 0;
}else {
seq++;
}

logger.info("THE SQUENCE IS :" +sb.toString());

return sb.toString();
}

}